"In my mind I have gone all over the universe, which may make it less important for me to make piddling little trips... I did enjoy seeing Stonehenge. It looked exactly the way I thought it would look."
- Isaac Asimov

"Since the ball is charged," Philippe answered, "it's easy to push it by charging up a metal plate placed near it. Of course, being negative matter, when you push it, it comes toward you.."

If there were such a thing, you might be able to use it to propel a space ship...

"In the experiment Hiroshi did," Philippe went on, "he used a metal plate with a negative electric charge so it would attract the positive electric charge of the ball. The ball pulled away in the opposite direction, pulling the test apparatus, the power supply, and Hiroshi along with it. When Hiroshi saw what was happening, he quickly turned the field off. He then had to reverse the field and push on the ball for a while to bring it to a halt again."

"It was just as Steve predicted," said Jim in awe. "A true reactionless space drive."

"A space drive?" exclaimed Randy in amazement.

"That is correct," said Philippe, his voice deepening as his face turned deadly serious. "When that ball of negative matter was pulling Hiroshi and his test apparatus along, there was nothing going in the opposite direction. There was no reaction mass and no energy source involved, but they moved nevertheless. That means a large enough negative-matter ball electrostatically coupled to a positive-matter spacecraft can propel the spacecraft at any acceleration the crew can stand for as long as you want.. Flight to the stars at near light speed is no longer a dream . . ."

Compare to cavorite from The First Men in the Moon (1901) by H.G. Wells, the gravity web from Whipping Star (1969) by Frank Herbert, the Granton motor from Into the Meteorite Orbit (1933) by Frank K. Kelly and Apergy from Across the Zodiac (1880) by Percy Greg.